The mechanism of the intestinal radiation syndrome will be delineated so that practical measures to prevent or ameliorate the syndrome can be recommended. Effects of abdominal radiation, bile salts and colestipol on intestinal transport of nutrients and electrolytes in rats will be quantified using radioisotope and electrophysiological techniques. Effects of abdominal x-radiation on bile acid composition and conjugation will be measured. Therapeutic measures utilizing colestipol, lecithin and neomycin will be evaluated. Whether the intestinal radiation syndrome is a form of cholerheic enteropathy, responsive to appropriate therapeutic measures will be clarified. Basic physiologic information of intestinal cellular function will be provided from data of electrophysiologic measurements of impedance and cable properties of the small intestinal mucosa.